The estimated peak in (129 × C57BL/6)F2 mice was at position 51.3 cM, whilst in the (129 × C57BL/6)F2.Apcs−/−animals it was was at position 71 cM, indicating that most likely these were two independent loci. Centimorgan positions were deduced by interval mapping, anchoring marker locations to data from http://www.informatics.jax.org. Dotted lines the indicate threshold over which linkage was considered suggestive, as defined in Materials and Methods.